Process of making primary arsanilic acid



entree stares PHILIP ADOLPH Kenna, or annanvjlvnw YORK, 4 8mm TO B. Rips or new YORK, n. Y., A CORPORATION or new YORK."

-ersnr caries.

rrtoc nss or MAKING. rmM RY ensnn nio ACID.

No Drawing".

Toallwkom itmaig concern: v Be it known thatPHrLIr ADoLrH Ko snn, a citizen oft-he United States, and of Albany, county of-Albany, and State of New York, has invented certain new and useful Improvements in Process of MaklngPriis a specification. V

This invention relates to improvements in the manufactureof primary arsanilic acid, or otherwise known-as p-amino-phenyl armary Arsanilic Acid, of which'the following sonic acid, which as the sodium salt has been known as atoxyl for many years.

(See Ehrhob and Bertheim, Berichte der deutscheu chemischen Gresellschaft, 40, 8292, (1907 i It finds usefulness in medicine and-in the manufacture of arsphenamine (salvarsan).

These authors, as well as many others in- 5 cludingG. T. Morganfin his book on Organie Compounds of Arsenic and Antimony, Longmans publishers, (1918), pages 64 and 154, mention that Bchamp (Comp.

rend, LVI, 1172, 1863) was the first to prepare this substance. In neither Bchamps article or in subsequent publications, such as Benda and Kahn (Berichte d er deutfchem. Gesell, 41,1672, 2367,1908) and Pyman and Reynolds (Transactions of the Journal of the Chem. Society (London), 98, 1184,

1908) are the disclosures suiiiciently accurate'a-nd definite to give primary ars anilic acid in substantial yields, withouthaving arsanilioacid (secondary) i. e., di-p-amino phenyl-arsinic acid as a by-product (see literature cited above). When the secondary arsanilic acid is present with the primary primary arsanilic acid free from secondary and practically free from coloring matter. Furthermore, it is not necessary to concentrate any liquors in vacuo or' otherwise, nor to decolorize with charcoal or any other means nor to distill oii' any aniline oil with steam or any other means.

The explanation for the method here dis- Specification of Lettersiatehti Application filed November 18, 191s. Serial no. 262,924.

closed follows from inspection of the rea'c tlon supposedly involved. I

- I j no aniline arsenic acid 7 Primary arsam'lic acid (p-aminophcnylarsenic acid) NH: Nfl

. In I arsenic 301d Secondary arsanilic I acid).

As may be seenv two molecules of anlllne Patented-Jan. 31, 1922.

QUIBIB & sons, j i

are necessary toinake the secondary arsanilic acid, and as Iiound, one can carryoutjthe. reaction with less than two molecules so that its formation as a by-product is hindered or absolutel prevented. This is contrary toall recorded directions. Furthermore, e31 periments show that below 180 .C. or thereabouts, even if two molecules of aniline are present for-one of arsenic acid, that the formatlon of the secondary arsanilic acid'does not take place to any extent,,while the for- 1119111011 of the primary arsanilic acid does go on to a considerable extent.

By using one or both of these schemes, the

primary arsanilic acid can be made easily and cheaply.

Tocarry out this invention, I prefer to go I y about it as follows:

One thousand cc. (about 1880 g.) of arsenic acid (containing 76% arsenic acid) are heatedin an open beaker or vessel, .at to C. for 12 to 15 hours, by means of an oil or Crisco bath. This concentrates the acid to practically 100% arsenic acid.

Fourteen hundred cc. (about 1400 g.) of aniline oil are cooled with an ice mixture to ed, a reflux condenser is then attached; for

one and a half hoursitis heated from 160, 170, and then 1 hour from 180 to 185 C. After allowing the mixture to cool somewhat 225 cc. of 6. normal sodium hydroxide and w 225 cc. of water are added, which causes the substance to dissolve and separates out the aniline oil left uncombined.

When the mixture is cool, the aqueous layer is drawn off, with the aid of a separatory funnel, and after shaking with 15 to 20 grains of infusorial earth or kaolin, it is filtered with suction. V

To the clear filtrate is added 100 cc. of 6N hydrochloric acid.

By means of cc. portions and further additions of 0.5 00., 1.0 ea, 2.00 cc., etc. of

GNHCl, one finds out if turther addition of acid to the whole filtrate will give an additional yield or not. hen after waiting a few minutes for the crystallization to take 7 place, and when the proper amount of hydrochloric acid has been determined on the small. aliquot portion, an equivalent amount of acid is then added to the whole filtrate. Usually the crystals fill the entire solution so that it has the appearance of being solid.

After standing for an hour or longer, the precipitate, which is white and crystalline, is filtered with suction. It isthen washed by suspending the precipitate in 200 cc. of water and filtering with suction. When all of the wash liquid has drained from the precipitate, it is dried byfanning, or. in any other I suitable way; The yield is from 20 to 30% j of the theory.

The product obtained by the above directions can, if necessary, be further purified by reprecipitation with alkali and acid, or by dissolving it in boiling water and allowing the same to cool The analysis of a crude product once purified' by hot water crystallization and dried in a vacuum desiccator. gave:

. As% N% Product 3 1.20 6.02 Product 34.50 6.13 Theory for primary acid 341.60- 6. 15 Theory for-secondary acid 25.65

hat is claimed is p 1. The process of makingprimary arsanilic acid without the simultaneous productlon or any appreciable amount of secondary arsanilic acid which comprises heating a mixf ture of about 3 to 4 molecular proportions of; aniline and 2 molecular proportions of arsanic acid first to a temperature of 160.to 170. C., and later at a temperature from 180-to 185 C. i

2. The process of making primary areanilic acid which comprises heating about ,3

molecular proportions of aniline. and E2 molecular proportions of arsenic acid'to a temperature which does'not exceed about 185 C. p

3.. The process of'making primary arse nilic acid without the simultaneous production of any appreciable amount of secondary arsanilic acid which comprises heating a mix:

v ture of about 3 to a molecular proportions of aniline and 2 molecular proportions of arsen cacid first to a temperature of to (1, for about 1%.hours andlater at a temperature from to (1, forabout 1 hour.

. Signed at Albany, inthe county of Albany,

and the State of New York, this 14th day of November, 1918.

V PHILIP ADOLPH' KOBER. 

